Photodynamic therapy (PDT) is continuing to undergo a rapid expansion in basic, preclinical and clinical research, and development as a modality for the diagnosis and treatment of cancer and other nonmalignant diseases. One of the major hindrances to this development is the lack of an efficient, reliable and easy to use laser source. In addition, a great deal of development is presently underway on 2nd generation photosensitizers, PSS, with absorption deeper in the red and near infrared spectra, <1200 nm. In phase-I a red Nd:YAG laser, 659nm, was developed and tested in combination with a 2nd generation PSS in a mouse tumor model. The laser is a KTP doubled 1318nm Nd:YAG and the photosensitizer the tin-IV etiopurpurin dichloride, SnET2. Animal testing of this combination of drug and laser determined it to be a viable PDT package. In phase-II it is the objective to further develop and refine the 659nm laser and quantitate its performance with three 2nd generation PSS. This will include the conversion of an existing clinical 532nm doubled Nd:YAG laser system to 659nm operation and its expanded testing with SnET2. Additionally, testing with the aspartyl-chlorin-E6. NP-6 PSS will be done. This testing will include direct comparison to the CW argon pumped dye laser to evaluate the impact of the 659nm ND: YAG's pulsed nature. Based on the results of the animal studies and the availability of the new 2nd generation PSS for clinical studies, limited phase-I clinical trials of the 659nm laser may be undertaken in the second year of the phase-II program. This PDT system package could provide a significant improvement in both the effectiveness and useability of PDT.